<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>经典 Header + Sidebar + Content 布局</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: Arial, sans-serif;
            background: linear-gradient(135deg, hsl(200, 60%, 85%), hsl(340, 70%, 85%));
            height: 100vh;
            display: flex;
            flex-direction: column;
        }

        /* Header */
        .header {
            height: 60px;
            background: rgba(255, 255, 255, 0.9);
            backdrop-filter: blur(10px);
            border-bottom: 1px solid rgba(0, 0, 0, 0.1);
            display: flex;
            align-items: center;
            justify-content: space-between;
            padding: 0 20px;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
        }

        .header .logo {
            font-size: 20px;
            font-weight: bold;
            color: #333;
        }

        .header .user-avatar {
            width: 40px;
            height: 40px;
            border-radius: 50%;
            background: url('https://via.placeholder.com/40') no-repeat center/cover;
            border: 2px solid #fff;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
        }

        /* Main Container */
        .main-container {
            display: flex;
            flex: 1;
            overflow: hidden;
        }

        /* Sidebar */
        .sidebar {
            width: 250px;
            background: rgba(255, 255, 255, 0.9);
            backdrop-filter: blur(10px);
            border-right: 1px solid rgba(0, 0, 0, 0.1);
            display: flex;
            flex-direction: column;
            padding: 20px;
            box-shadow: 2px 0 10px rgba(0, 0, 0, 0.1);
        }

        .sidebar ul {
            list-style: none;
        }

        .sidebar ul li {
            margin-bottom: 15px;
            cursor: pointer;
            padding: 10px;
            border-radius: 5px;
            transition: background 0.3s ease;
        }

        .sidebar ul li:hover {
            background: rgba(0, 0, 0, 0.1);
        }

        /* Content */
        .content {
            flex: 1;
            padding: 20px;
            overflow-y: auto;
            background: rgba(255, 255, 255, 0.8);
            backdrop-filter: blur(10px);
        }
    </style>
</head>
<body>
<!-- Header -->
<div class="header">
    <div class="logo">LOGO</div>
    <div class="user-avatar"></div>
</div>

<!-- Main Container -->
<div class="main-container">
    <!-- Sidebar -->
    <div class="sidebar">
        <ul>
            <li>仪表盘</li>
            <li>用户管理</li>
            <li>设置</li>
            <li>退出登录</li>
        </ul>
    </div>

    <!-- Content -->
    <div class="content">
        <h1>欢迎来到内容区域</h1>
        <p>这里是主要内容区域，您可以在这里显示动态数据、图表或其他内容。</p>
    </div>
</div>
</body>
</html>
